摘要
采用并流共沉淀法制备CuO/ZnO/Al2O3甲醇合成催化剂前体,在通入CO2条件下老化,采用XRD、FT-IR、DTG、H2-TPR、XPS等表征手段对制备的前体及焙烧后的催化剂进行表征,研究不同CO2通入量对前体晶相转变、微观结构及其焙烧后催化性能的影响。研究结果表明,老化阶段通入CO2后,沉淀母液的pH值趋于7,产生CO32离子,进而影响Zn2+的沉淀,促进Cu2+进入Zn5(CO3)2(OH)6晶格中取代Zn2+形成绿铜锌矿(Zn,Cu)5(CO3)2(OH)6物相,有助于增强焙烧后催化剂的Cu-Zn之间协同作用,增加活性组分Cu分散度。CO2通入量为40 mL/min时,制备的催化剂在浆态床合成甲醇过程中表现出良好的催化活性和稳定性,甲醇时空收率(STY)达到301.78 g/(kg h),失活率仅为0.15%/d,与未通入CO2辅助老化制备的催化剂相比,时空收率提高了9.72%,平均失活率降低了33.33%。
The CuO/ZnO/Al2O3 catalysts were prepared by co-precipitation,and the effects of CO2 addition during the aging process on the phase composition of precursors,the microstructure of the calcined catalysts and catalytic performance for slurry phase methanol synthesis were investigated. The characterization by XRD,FT-IR,DTG,H2-TPR and XPS showed that adding CO2 helps to keep the mother liquor pH close to neutral,and generates CO32？ ions,thus to facilitate Zn^2＋ precipitate and to promote Cu^2＋ into Zn5（CO3）2（OH）6 lattice substitution of Zn^2＋ formation the aurichalcite（Zn,Cu）5 （CO3）2（OH）6,leading to the improvement of content in precursors. While the catalyst is calcined,it exhibits a strong interaction between CuO and ZnO,well dispersion of CuO crystal particles around ZnO surface,and the best catalytic performance,including the methanol space-time yield （STY） and the stability. While the volume flow of CO2 was 40 mL/min,the methanol space-time yield （STY） and deactivation rate of the catalyst were 302.45 g/（kg·h） and 0.15%/d,respectively. Compared with the catalyst prepared without adding CO2 in the aging process,the methanol STY and deactivation rate of the catalyst were increased and decreased by 7.36% and 28.57%,respectively.
出处
《化工进展》
EI
CAS
CSCD
北大核心
2013年第11期2644-2649,2660,共7页
Chemical Industry and Engineering Progress
基金
国家973计划(2012CB723105)
国家自然基金青年科学基金(21106092)项目
